1. Field of the Invention
The present invention relates to method and apparatus for vulcanizing pneumatic tires.
2. Description of the Related Art
Conventional technology for vulcanizing tires is disclosed, for example, in JP-2000-326332A. In this instance, when a plurality of arcuate sector mold members aligned along the peripheral direction assume radially outermost positions, an unvulcanized tire is transferred and loaded onto the lower mold member and the upper mold member is moved toward the lower mold member while the sector mold members are synchronously displaced radially inwards, thereby hermetically enclosing the unvulcanized tire in a mold space formed by the upper mold member, the lower mold member and the sector mold members.
Subsequently, the unvulcanized tire is vulcanized in the mold space to give a vulcanized tire, and the sector mold members are then synchronously displaced radially outwards by the displacing means while the upper mold member is moved away from the lower mold member, so as to allow removal of the vulcanized tire out of the molds.
In the above-mentioned conventional technology, however, the tread of the pneumatic tire has a larger diameter as it approaches to the equator of the tire since the tread has a crown shape, so that the upper and lower ends of the inner periphery of the sector mold member protrude radially inwards as compared with the center. As a result, when the unvulcanized tire is carried into the sector mold, or when the vulcanized tire is carried out of the sector mold, the sector mold members have to be moved radially outwards by a sufficient amount so as to avoid the unvulcanized tire or the vulcanized tire from interfering with the protruded upper ends of the inner periphery of the sector molds. Therefore, the conventional technology requires a large sized facility and higher cost.